A method for manufacturing ceria nanoparticle using low temperature sintering method

Abstract

The present invention relates to a method for manufacturing ceria nanoparticles using a low-temperature calcination method, and more specifically, to a method for manufacturing ceria nanoparticles comprising: (a) a step of preparing a mixture by mixing cerium oxide and a reducing agent; (b) a step of preparing nanoparticles by heat-treating the mixture; (c) a step of washing the nanoparticles; and (d) a step of drying the washed nanoparticles.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing ceria nanoparticles using a low-temperature calcination method, and more specifically, to a method for manufacturing ceria nanoparticles comprising: (a) a step of preparing a mixture by mixing cerium oxide and a reducing agent; (b) a step of preparing nanoparticles by heat-treating the mixture; (c) a step of washing the nanoparticles; and (d) a step of drying the washed nanoparticles. Background Technology

[0003] As semiconductor devices become more highly integrated and perform better, wiring pattern linewidths are becoming finer and structures are becoming increasingly multilayered; therefore, interlayer flatness in each process is crucial for improving photolithography precision.

[0004] The chemical-mechanical polishing (CMP) process is currently the most prominent planarization technology, and it is classified into oxide CMP, metal CMP, and poly-silicon (poly-Si) CMP processes depending on the material to be polished.

[0005] Initially, CMP slurry compositions containing silica particles were mainly used to polish oxide films, but as design rules became smaller and devices became thinner requiring high planarization, CMP slurry compositions containing cerium oxide (ceria) particles, which have a high polishing selectivity for wafers containing heterogeneous films, are being applied.

[0006] Meanwhile, a slurry composition containing ceria particles has a higher polishing speed compared to a slurry composition containing silica particles, but scratches may occur on the surface to be polished.

[0007] Methods for manufacturing ceria nanoparticles include pyrolysis, reduction, precipitation, and calcination. Among these, the calcination method can mass-produce ceria nanoparticles with excellent properties such as heat resistance and wear resistance, but it has the disadvantage of requiring high-temperature equipment and a complex manufacturing process.

[0008] Therefore, there is a need to develop technology for a method of manufacturing ceria nanoparticles that has a simple manufacturing process, allows for mass production at low temperatures, and possesses excellent thermal stability, dispersion stability, stability over time, polishing speed, polishing efficiency, and selective polishing characteristics. Prior art literature

[0010] Korean Published Patent No. 10-2013-0078791 Korean Published Patent No. 10-2024-0138745 The problem to be solved

[0011] The present invention aims to solve the problems of the prior art and provides a method for manufacturing ceria nanoparticles for a polishing slurry composition that has a simple manufacturing process, can be mass-produced at low temperatures, and has excellent thermal stability, dispersion stability, stability over time, polishing speed, polishing efficiency, and selective polishing characteristics. means of solving the problem

[0013] To achieve the above objectives, the present invention comprises the step of (a) preparing a mixture by mixing cerium oxide and a reducing agent;

[0014] (b) a step of heat-treating the above mixture to produce nanoparticles;

[0015] (c) a step of washing the nanoparticles; and

[0016] (d) a step of drying the washed nanoparticles; a method for manufacturing ceria nanoparticles is provided.

[0017] In one embodiment of the present invention, step (a) is characterized by the weight ratio of cerium oxide to reducing agent being 1:1 to 1:9.

[0018] In one embodiment of the present invention, step (b) is characterized by heat-treating the mixture at 100 to 500°C for 10 to 500 minutes.

[0019] In one embodiment of the present invention, step (b) is characterized by heat-treating the mixture in a nitrogen, argon, or helium atmosphere.

[0020] In one embodiment of the present invention, step (d) is characterized by drying the washed nanoparticles at 40 to 150°C for 1 to 50 hours.

[0021] In addition, the present invention provides ceria nanoparticles produced by the above-described manufacturing method. Effects of the invention

[0023] The present invention can provide a method for manufacturing ceria nanoparticles for a polishing slurry composition that has a simple manufacturing process, can be mass-produced at low temperatures, and has excellent thermal stability, dispersion stability, stability over time, polishing speed, polishing efficiency, and selective polishing characteristics. Brief explanation of the drawing

[0025] Figure 1 shows SEM images of ceria nanoparticles of the present invention: (a) before heat treatment, (b) heat treatment at 300°C, (c) heat treatment at 400°C, (d) heat treatment at 500°C. Figure 2 shows the XRD results of the ceria nanoparticles of the present invention: (a) before heat treatment, (b) heat treatment at 300°C, (c) heat treatment at 400°C, (d) heat treatment at 500°C. Specific details for implementing the invention

[0026] The present invention will be described in detail below based on the following examples. The terms and examples used in this invention are merely illustrative to explain the invention more specifically and to aid the understanding of those skilled in the art, and the scope of the rights of the present invention should not be interpreted as being limited thereto.

[0027] Unless otherwise defined, technical and scientific terms used in this invention represent the meanings commonly understood by those skilled in the art to which this invention pertains.

[0029] The present invention comprises the step of (a) preparing a mixture by mixing cerium oxide and a reducing agent;

[0030] (b) a step of heat-treating the above mixture to produce nanoparticles;

[0031] (c) a step of washing the nanoparticles; and

[0032] (d) a step of drying the washed nanoparticles; the present invention relates to a method for manufacturing ceria nanoparticles comprising the above steps.

[0034] Step (a) above can be prepared by mixing cerium oxide and a reducing agent for 10 to 500 minutes.

[0035] The above cerium oxide may be cerium oxide (III), cerium oxide (IV), etc.

[0036] The above reducing agent may be NaBH4, LiAlH4, DIBAL-H (diisobutylaluminium hydroxide), ascorbic acid, Na2S2O4 (sodium dithionite), etc.

[0037] In the present invention, a mixture of NaBH4 and LiAlH4 can be used as a reducing agent. At this time, the weight ratio of NaBH4 and LiAlH4 is preferably 60 to 80:20 to 40, and when the weight ratio satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0038] In addition, the present invention may use a mixture of NaBH4, LiAlH4, and DIBAL-H as a reducing agent. In this case, the weight ratio of NaBH4, LiAlH4, and DIBAL-H is preferably 100:20 to 40:5 to 20, and when the weight ratio satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0039] In addition, the above step (a) preferably has a weight ratio of cerium oxide to a reducing agent of 1:1 to 1:9. When the weight ratio satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0041] In addition, the above mixture may further include a ceria precursor.

[0042] The above ceria precursor may be one or more selected from cerium carbonate, cerium sulfate, cerium acetate, cerium nitrate, and cerium chloride.

[0043] The present invention may use a mixture of cerium carbonate and cerium acetate as a ceria precursor.

[0044] At this time, the weight ratio of the cerium carbonate and cerium acetate is preferably 60 to 80:20 to 40, and when the weight ratio satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0045] In addition, the present invention may use a mixture of cerium carbonate, cerium acetate, and cerium nitrate as a ceria precursor.

[0046] At this time, the weight ratio of the above cerium carbonate, cerium acetate, and cerium nitrate is preferably 100:20 to 40:5 to 20, and when the weight ratio satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0047] The content of the above ceria precursor is preferably 2 to 10 parts by weight per 100 parts by weight of cerium oxide, and when the content satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0049] The above step (b) can produce nanoparticles by heat-treating the mixture.

[0050] In the present invention, it is preferable to heat-treat the mixture at 100 to 500°C for 10 to 500 minutes in a nitrogen, argon, or helium atmosphere, and when the heat treatment conditions satisfy the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0051] In addition, the above step (b) is a primary heat treatment step for producing a primary product by heating the mixture;

[0052] A secondary heat treatment step of heating the primary product to produce a secondary product;

[0053] A third heat treatment step of heating the above secondary product to produce a tertiary product; and

[0054] It may include a fourth heat treatment step of heating the above third product to produce a fourth product.

[0055] By performing the above heat treatment step in multiple stages, the size, distribution, shape, density, and crystallinity of the manufactured ceria particles are uniform, thereby improving dispersibility, polishing speed, and polishing efficiency.

[0057] The above first heat treatment step can produce a first product by heat treating at 100 to 200°C for 10 to 150 minutes.

[0058] When the heat treatment conditions satisfy the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0060] The above second heat treatment step can produce a second product by heat treating at 210 to 300°C for 10 to 150 minutes.

[0061] When the heat treatment conditions satisfy the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0063] The above third heat treatment step can produce a third product by heat treating at 310 to 400°C for 10 to 150 minutes.

[0064] When the heat treatment conditions satisfy the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0066] The above fourth heat treatment step can produce a fourth product by heat treating at 410 to 500°C for 10 to 150 minutes.

[0067] When the heat treatment conditions satisfy the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0069] The cerium oxide prior to the above heat treatment has a needle-shaped structure, and the nanoparticles produced through heat treatment can have a spherical shape.

[0071] Step (c) above can remove impurities such as sodium by washing the nanoparticles several times with distilled water, alcohol (methanol, ethanol, isopropyl alcohol, butanol, etc.).

[0073] Step (d) above may dry the washed nanoparticles at 40 to 150°C for 1 to 50 hours.

[0075] In addition, the present invention relates to ceria nanoparticles produced by the above-described manufacturing method.

[0076] The method for manufacturing ceria nanoparticles using the low-temperature calcination method of the present invention can provide ceria nanoparticles for polishing slurry compositions that have a simple manufacturing process, enable mass production at low temperatures, and have excellent thermal stability, dispersion stability, stability over time, polishing speed, polishing efficiency, and selective polishing characteristics.

[0077] The above ceria nanoparticles have excellent thermal stability, dispersion stability, stability over time, polishing speed, polishing efficiency, and selective polishing characteristics, and can minimize scratches on the surface to be polished, so they can be used for polishing slurry compositions.

[0079] In addition, the present invention may further include a step of surface treating the dried nanoparticles after step (d).

[0080] The above ceria nanoparticles can be surface-treated with a copolymer of an acrylate group-containing silane coupling agent, 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), and glycidyl methacrylate.

[0081] By using the above-mentioned surface-treated ceria nanoparticles, dispersibility, polishing speed, and polishing efficiency can be improved.

[0082] The above acrylate group-containing silane coupling agents include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, methacryloxymethyltriethoxysilane, and methacryloxymethyltrimethoxysilane.

[0083] It is preferable that the weight ratio of the above acrylate group-containing silane coupling agent, 2-hydroxyethyl acrylate (HEA), 2-hydroxyethyl methacrylate (HEMA), and glycidyl methacrylate is 2~10:100:20~50:10~30.

[0084] The content of the copolymer is preferably 1 to 10 parts by weight per 100 parts by weight of ceria nanoparticles, and when the content satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0086] In addition, the ceria nanoparticles can be surface-treated with an acrylic mixture comprising methyl methacrylate, acrylic acid, and 2-hydroxyethyl acrylate (HEA).

[0087] By using the above-mentioned surface-treated ceria nanoparticles, dispersibility, polishing speed, and polishing efficiency can be improved.

[0088] The weight ratio of the above methyl methacrylate, acrylic acid, and 2-hydroxyethyl acrylate (HEA) is preferably 100:20 to 50:10 to 30.

[0089] The content of the above acrylic mixture is preferably 1 to 10 parts by weight per 100 parts by weight of ceria nanoparticles, and when the content satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0091] In addition, the above ceria nanoparticles can be surface-treated with a silane compound.

[0092] The above silane compounds may include alkoxysilanes such as tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS), sodium silicate, potassium silicate, silicon tetrachloride, etc., without limitation.

[0093] The content of the above silane compound is preferably 1 to 10 parts by weight per 100 parts by weight of ceria nanoparticles, and when the content satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0094] The present invention may use a mixture of tetramethoxysilane and tetraethoxysilane as silane compounds.

[0095] At this time, the weight ratio of the tetramethoxysilane and tetraethoxysilane is preferably 60 to 80:20 to 40, and when the weight ratio satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0097] In addition, the ceria nanoparticles can be surface-treated with a composition prepared by mixing the acrylic mixture and the silane compound.

[0098] At this time, the weight ratio of the acrylic mixture and the silane compound is preferably 60 to 80:20 to 40, and when the weight ratio satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0099] The content of the above composition is preferably 1 to 10 parts by weight per 100 parts by weight of ceria nanoparticles, and when the content satisfies the above numerical range, dispersibility, polishing speed, and polishing efficiency can be maximized.

[0101] The present invention will be described in detail below through examples and comparative examples. The following examples are merely illustrative for the implementation of the present invention, and the scope of the present invention is not limited by the following examples.

[0103] (Example 1)

[0104] A mixture was prepared by mixing cerium oxide (IV) and NaBH4 in a weight ratio of 1:5 for 30 minutes.

[0105] Nanoparticles were prepared by heat-treating the above mixture at 300°C for 120 minutes in a nitrogen atmosphere.

[0106] The above nanoparticles were washed three times with distilled water.

[0107] Ceria nanoparticles were prepared by drying the above-mentioned washed nanoparticles at 80°C for 24 hours.

[0109] Figure 1 shows an SEM image of the ceria nanoparticles of the present invention.

[0110] Before heat treatment, the ceria particles (a) have a needle-shaped structure of micrometer size, and through heat treatment, they become spherical and have a smooth surface structure.

[0112] Figure 2 shows the XRD results of the ceria nanoparticles of the present invention.

[0113] Ceria nanoparticles exhibit peaks at the (111), (200), (220), (331), and (222) planes, which are the representative lattice structures of ceria, and from this, it can be confirmed that a ceria crystal structure is formed.

[0114] It is observed that as the heat treatment temperature increases, the crystallinity decreases due to oxygen defects, resulting in a weakening of the peak intensity.

[0116] (Example 2)

[0117] Ceria nanoparticles were prepared in the same manner as in Example 1, except that cerium oxide (IV) and NaBH4 were used in a weight ratio of 1:0.8.

[0119] (Example 3)

[0120] Ceria nanoparticles were prepared in the same manner as in Example 1, except that cerium oxide (IV) and NaBH4 were used in a weight ratio of 1:12.

[0122] (Example 4)

[0123] Ceria nanoparticles were prepared in the same manner as in Example 1, except that a mixture of NaBH4 and LiAlH4 was used instead of NaBH4.

[0124] At this time, the weight ratio of the above NaBH4 and LiAlH4 was adjusted to 70:30.

[0126] (Example 5)

[0127] A first heat treatment step of preparing a first product by heating the mixture at 150°C for 30 minutes instead of heat-treating the mixture at 300°C for 120 minutes;

[0128] A secondary heat treatment step of preparing a secondary product by heating the primary product at 250°C for 30 minutes;

[0129] A third heat treatment step of preparing a third product by heating the above second product at 350°C for 30 minutes; and

[0130] Ceria nanoparticles were prepared in the same manner as in Example 1, except that a fourth heat treatment step was used to prepare a fourth product by heating the above third product at 450°C for 30 minutes.

[0132] (Example 6)

[0133] An acrylic mixture was prepared by mixing methyl methacrylate, acrylic acid, and 2-hydroxyethyl acrylate (HEA).

[0134] At this time, the weight ratio of methyl methacrylate, acrylic acid, and 2-hydroxyethyl acrylate (HEA) was adjusted to 100:30:20.

[0135] The ceria nanoparticles prepared in Example 1 were surface-treated with the acrylic mixture.

[0136] At this time, the content of the acrylic mixture was adjusted to 5 parts by weight per 100 parts by weight of ceria nanoparticles.

[0138] (Comparative Example 1)

[0139] Ceria nanoparticles were prepared in the same manner as in Example 1, except that cerium oxide (IV) was heat-treated at 600°C for 6 hours in a nitrogen atmosphere.

[0141] (Target for grinding)

[0142] The wafer used was a flat silicon oxide film.

[0144] (CMP process conditions)

[0145] The polishing process conditions are as shown in Table 1 below.

[0147] CMP parameter CMP condition equipment AP-300(CTS) Polishing pad IC-1010(DAW) Slurry inflow rate 250㎖ / min Head speed 87rpm Table speed 93rpm enter 5.0 psi Polishing time 60 seconds

[0149] (Grinding speed)

[0150] The thickness of the wafer specimens before and after polishing was verified using ST-5030 (K-MAC Corp.). To prevent measurement errors, 49 identical points were measured along the X-axis from the center to the edge of each wafer and averaged (unit: Å / min).

[0152] (Uniformity)

[0153] The uniformity of the wafer specimen was measured after polishing.

[0155] (Scratch status)

[0156] After polishing and cleaning the substrate, defects and scratches were observed using an optical microscope and classified as excellent, good, average, or poor.

[0158] The characteristics of the polishing slurry composition containing ceria nanoparticles prepared from the above examples and comparative examples were evaluated, and the results are shown in Table 2 below.

[0160] Polishing speed (Å / min) Uniformity (%) Whether there are scratches Example 1 1,412 8.7 excellence Example 2 1,194 12.1 commonly Example 3 1,209 13.0 commonly Example 4 1,517 7.4 eminence Example 5 1,563 6.8 eminence Example 6 1,635 7.0 eminence Comparative Example 1 1,080 16.2 error

[0162] From the results of Table 2 above, it can be seen that Examples 1 to 6 have excellent polishing speed, uniformity, and scratch occurrence characteristics for silicon oxide films.

[0163] In particular, Examples 1, 4 to 6 have the best characteristics.

[0164] On the other hand, it can be seen that Comparative Example 1 has inferior characteristics compared to the example.

Claims

Claim 1 (a) A step of preparing a mixture by mixing cerium oxide and a reducing agent; (b) a step of heat-treating the above mixture to produce nanoparticles; (c) a step of washing the nanoparticles; and (d) a step of drying the washed nanoparticles; a method for manufacturing ceria nanoparticles comprising. Claim 2 In paragraph 1, A method for manufacturing ceria nanoparticles, characterized in that step (a) above has a weight ratio of cerium oxide to a reducing agent of 1:1 to 1:

9. Claim 3 In paragraph 2, A method for preparing ceria nanoparticles, characterized in that step (b) above involves heat-treating the mixture at 100 to 500°C for 10 to 500 minutes. Claim 4 In paragraph 3, A method for preparing ceria nanoparticles, characterized in that step (b) above involves heat-treating the mixture in a nitrogen, argon, or helium atmosphere. Claim 5 In paragraph 4, A method for preparing ceria nanoparticles, characterized in that step (d) above involves drying the washed nanoparticles at 40 to 150°C for 1 to 50 hours. Claim 6 Ceria nanoparticles manufactured by the manufacturing method of claim 1.

Images